Funnel-web spiders

Species of the genera Hadronyche. Illawara and Atrax, family Hexathelidae

Funnel-webs are the most dangerous of all spiders: death from a bite has occurred in as little as 15 minutes. Sadly, many harmless dark spiders are mistaken for funnel-webs and unnecessarily killed.

Female Toowoomba Funnel-web spider (Hadronyche infensa).

Funnel-webs range from small to large, but most are medium-sized spiders with two small finger-like spinnerets seen at the end of the body. They are shiny, black-headed spiders with a black to blue-black body and long legs.

Spiders that make funnel-shaped webs also occur in Europe and America but are harmless and unrelated to the Australian funnel-webs whose web itself is not really funnel-shaped.

The Sydney Funnel-web is one of the best known species.

Funnel-webs are found in coastal eastern Australia, including Tasmania, around Adelaide and the Eyre Peninsula. They seem to be limited to areas where the maximum summer temperature is not so high.

In Queensland, they occur almost continuously north to Kroombit Tops, just west of Gladstone, and then are not found again until very remote mountains just west of Mossman. In Queensland’s south-east, they are most common on rainforest covered mountain ranges but also along the gullies of rivers and creeks flowing off them, including Kedron Brook, where a lady in Newmarket was bitten.

The spiders also occur on Fraser Island (but have not been found on similar Moreton or Stradbroke Island). Here, they are unusual in that they are found, sometimes in quite high numbers, in lowland rainforest and moist gullies as well as in the eucalypt-Banksia communities around Orchid Beach. Burrowing on Fraser Island presents a challenge to these spiders whose burrows are up to almost a metre deep in the crumbling sand. The spiders do not occur on the beaches themselves. The webs are often hidden at the bases of shrubs and trees.

Typically, 2 to 3 entrance tubes across the ground join together, forming the funnel which is often hidden in the top layers of the soil. Each tube is a dirty silken sock with the lower part held out by long strands of tough silk. Rarely are the upper parts of the entrances held open but then, too, the funnel is noticeable.

The spider is often noticed only as a moving bulge in the tube until it launches quickly upon its much-loved prey, the vegetarian millipedes. The fine trembling movements of the millipede are the key to attracting the spider out; larger six-legged animals like crickets and beetles are usually ignored.

Most burrows are built on the ground but some occur on trees and those are believed to be the burrowows of the Northern Rivers Funnel-web (Hadronyche formibabilis). These spiders grow to a large size. One of our specimens (QM S11042) is 57mm from chelicerae to spinnerets, with fang length of 10.42mm, and is believed to be the largest recorded specimen.

Funnel-webs are exclusively nocturnal, both hunting and mating during the night.

In southern Queensland, male Funnel-webs are active from August through to May, depending on the season, but usually their peak activity period is from November through to February.

Until males become adult, they burrow and behave like females. During late Spring and Summer, triggered by the onset of heat and rain, the males shed their skins inside their burrow, becoming sexually mature. Males wander on rainy nights in search of females but often get lost and wander into our houses.

At dawn, males seek moist dark shelter under logs, in shallow tubes and amongst clumps of leaves. In this situation we may stumble across them but so too does one of their many predators, the large black rainforest skink, called a Land Mullet. The next morning they wander again searching for a female. Often, males get totally confused and get eaten by a female that is not their species.

Male Funnel-webs are attracted to water and may be found in swimming pools. Although they may have been underwater for sometime, they may be still alive and may be dangerous.

Funnel-webs cannot jump or leap and cannot climb smooth vertical surfaces but they can and climb rough walls or wood.

Funnel-webs are remarkable in some aspect of their venom and its delivery.

Although quickly fatal to man, the venom is harmless to dogs, cats, adult mice and guinea pigs. Since primates, including humans, were not present when Funnel-web venom evolved about 40 million years ago, the high toxicity to us is an accident of evolution. The primary function of the venom is to quickly paralyse the spider's usual prey, vegetarian millipedes. Those millipedes need a protection device and that is a highly toxic spray based upon cyanide, a fast-acting poison even to man. The funnelweb’s venom paralyses the millipede, preventing the spray being used. However, in humans, the venom forces the nerves to fire rapidly and randomly and thus the heart and lung tremble or fibrillate and we basically drown in our body's fluid.

Funnel-web venom is formed in a large spindle-shaped gland in the biting chelicerae; the gland is surrounded by a muscle which allows the spider to control the release or retraction of the venom. Often, with very little provocation, funnel-webs will rise into the defensive pose with a drop of highly toxic venom hanging off each fang.

One drop is enough to kill a man but often much of that drop is lost through contact with clothing. Because of that, far more bites occur than serious envenomations, and far more such envenomations have occurred that deaths. In medical records, 14 people have died from the bite of Funnel-webs and no deaths have occurred since the production of the antivenom in 1981. All deaths have occurred from the bite of male Funnel-webs and have been in New South Wales where the incidence of Australia’s highest population density (Sydney) and a widespread occurrence of Funnel-webs signals maximal danger.

Funnel-web venom is a cocktail of chemicals which changes its composition as it passes from venom gland to fang tip but the venom of each species has a unique dangerous component, usually named using the species as the source, i.e., robustoxin is found in Atrax robustus.

Originally, males were thought to be up to 6 times more toxic than females and Toowoomba Funnel-web (Hadronyche infensa) was supposed to be the most venomous species; both ideas have proven to be incorrect. Certainly, both in number of deaths and tested toxicity, the Sydney Funnelweb (Atrax robustus) is the most toxic Funnel-web species known.

The Wet Tropics Funnel-web (Hadronyche anzses), because it occurs so far (over 1000km) north of the next nearest species, is likely to have a very different venom which developed in long isolation from the other species.

Treatment of Funnel-web bite

Two groups of Funnel-web species are grouped into three genera: Atrax, presently includes the Sydney Funnel-web (Atrax robustus) and two new species described by Gray, 2010, Atrax yorkmainorum from the ACT and adjacent areas of New South Wales and Atrax sutherlandi from south-eastern New South Wales and eastern Victoria. A new genus and species, Illawarra wisharti, has been described from the Illawarra region, just south of Sydney. The biggest genus is Hadronyche (pronounced had-ron-ee-key) and includes all other species including Hadronyche cerberea which also occurs in Sydney.

Queensland species are:

Toowoomba Funnel-web (Hadronyche infensa), the most common species in south-east Queensland

The Greater (from higher elevations( and Lesser Lamington Funnel-webs (Hadronyche valida and Hadronyche lamingtonensis), both found at Lamington National Park and Mount Tamborine National Parks

Monteith's Funnel-web (Hadronyche monteithi), from near Killarney

Northern Rivers Funnel-web (Hadronyche formibabilis)

Wet Tropics Funnel-web (Hadronyche anzses)

Conondale Funnel-web (Hadronyche raveni)

Recognition of species requires a careful examination of a preserved spider, most preferably an adult male. Identification to species from photographs or using only females is almost impossible.

The process can be simplified considerably using locality guides, as usually only one or two species are present in any location and most locations are well known. Eventually, as with many mygalomorph spiders, DNA methods will be required but will need considerable collection of fesh specimens from each locailty. However, an even stronger guide is in the venom itself which is different even between populations and can be extracted without harm to the spider.

Adult male Funnel-webs are the easiest to identify but again need first to be preserved. In Queensland, in only the giant Northern Rivers Funnel-web, Hadronyche formibabilis, is there a mating spur on the middle of the second leg. In all other Queensland species, both the first and second legs are spiny but lack any spur.

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